The present invention relates to a seat suspension vibration damper for dampening vibrations of a vehicle seat.
Numerous vehicle seat suspensions are known, including those having air bag or air spring suspensions for resiliently supporting a seat in a selected position. In such suspension systems, pressurized air is delivered to or exhausted from the air bag to adjust the elevation of the seat. The use of an air bag permits upward and downward vibrations of the seat. To counteract these vibrations, shock-absorbing cylinders have been used to dampen the seat vibrations.
In one known approach, as the elevation of the seat suspension is changed by inflating or deflating the air bag, the shock absorbing cylinder has a piston supporting rod which extends or retracts, depending upon the direction in which the seat elevation is changed. In this approach, the shock absorbing cylinder must be capable of extension and retraction throughout the entire range of seat elevation adjustment. In addition, these seat suspension systems are understood to use shock absorbing cylinders with pistons that apply a constant dampening force over the full stroke of the piston. If the dampening force were non-constant in such systems, problems would ensue. For example, in such systems a non-constant dampening force would mean that the ride provided by the seat would vary depending upon the seat elevation.
U.S. Pat. No. 3,951,373 illustrates one form of seat suspension utilizing a shock absorbing cylinder and an air bag or air spring. In this construction, the shock absorber is understood to have a stroke which is capable of extending and retracting throughout the full range of seat height adjustment. However, in this construction, a hand knob may be operated to adjust the throw of a shaft to thereby change the effective length of the shock absorber.
Although numerous seat suspension systems are known and a number of them have mechanisms for dampening seat vibrations, a need nevertheless exists for an improved vibration damper for a seat suspension system having new and non-obvious differences from vibration dampers used in known systems.
A vibration damper is described for use in seat suspension systems such as those of the type which support a seat above the floor of a vehicle, the seat being raisable and lowerable to support the seat at various selected elevations relative to the floor of the vehicle, and wherein movement of the seat from a selected elevation in response to vibrations is permitted. The vibration damper is operable to dampen these seat vibrations when the vibration damper is operatively coupled to the seat suspension system. In one illustrated form, the vibration damper comprises a self-contained module which is convenient to install in a seat suspension system. Also, removal thereof, for example in the case of repair or replacement, is relatively convenient.
In one illustrated embodiment, the vibration damper includes a first member adapted for coupling to one of the vehicle and seat. The first member may comprise a housing or may take other configurations. The phrases xe2x80x9cfor coupling toxe2x80x9d or xe2x80x9ccoupled toxe2x80x9d one of the vehicle and seat includes direct and indirect connection to one of these components. For example, the first member may be connected to a base or other component of a seat support which is affixed to the vehicle. Alternatively, the first member may be directly or indirectly connected to the seat, for example to a platform or seat support upon which a seat is mounted or directly to the seat. In addition, the vibration damper of this embodiment includes a shock absorber adapted to be coupled to the other of the vehicle and seat, again, direct or indirect coupling is contemplated. Moreover, a latch is adapted to selectively couple the first member to the shock absorber such that when the shock absorber and first member are coupled together the shock absorber applies a dampening force to the seat. In addition, when the shock absorber and first member are decoupled from one another the shock absorber is relieved from applying a dampening force to the seat.
In accordance with a further aspect of an embodiment, the first member may comprise a housing with an interior and an exterior with the shock absorber being substantially positioned or disposed within the interior of the housing and thereby protected by the housing. In addition, the latch may also be carried by the housing and operated by a latch actuator to selectively couple and decouple the shock absorber to and from the housing to thereby selectively apply and relieve the application of the dampening force to the seat. The latch actuator may be a fluid actuator, such as a pneumatic actuator, an electrically operated actuator, such as a motor, for shifting the latch to couple and decouple the shock absorber in response to the actuator. Although less preferred, a mechanical actuator may be used of the type which is manually shifted to couple and decouple the shock absorber to and from the housing.
As another aspect of an embodiment, the shock absorber may include a cylinder or exterior housing with a latch gripping surface carried by the cylinder. The latch gripping surface may be a friction enhanced surface or may comprise a mechanism mounted to the cylinder such as a plurality of teeth. The shock absorber also may include a dampening piston within the cylinder and a piston rod coupled to the piston and having an end portion projecting outwardly from the piston for coupling to the other of the vehicle and seat (the other of the vehicle and seat in this case being the other of these components to which the first member or housing is not coupled).
The latch may include at least one latch arm with a latch surface which may be a friction enhanced surface. Like the latch gripping surface, the latch surface may comprise a plurality of teeth. The latch arm may be coupled to the first member or housing with the latch arm being movable between first and second positions. When the latch arm is in the first position, the latch surface of the latch arm engages the latch gripping surface carried by the cylinder to thereby couple the shock absorber to the first member or housing. When the latch arm is in the second position, the latch surface is disengaged from the latch gripping surface. The latch arm may be pivoted to the first member or housing, in the case wherein the first member takes the form of a housing, for pivoting movement between the first and second positions. In one specific approach, both the first member, such as the housing, and latch arm are pivotally coupled to said one of the vehicle and seat for pivoting about a common first pivot axis.
As another aspect of an illustrated embodiment, the shock absorber cylinder may be slidably coupled to the first member, or housing in the case the first member takes the form of a housing, for sliding movement relative to the first member. Thus, the first member may comprise a housing having a first side wall with an exterior surface at the exterior of the housing and an interior surface at the interior of the housing. The first side wall may include first and second side wall portions spaced apart from one another to define a guide slot therebetween. The slide element may be mounted to the cylinder and slidably coupled to the first and second side wall portions such that the slide element slides along the guide slot and guides the sliding motion of the cylinder and thereby the shock absorber relative to the housing. This sliding inter-connection of these elements may be independent of the operation of the latch.
In a more specific approach, the cylinder may be substantially disposed within the housing. In addition, the slide elements may include first and second inter-connected slide members which sandwich the respective first and second side wall portions therebetween. In this case, the first slide member may be positioned substantially within the housing and may include respective first and second teeth containing flange portions extending in a direction away from the first side wall of the housing, the first and second teeth containing flange portions being spaced apart from one another and positioned at opposite sides of the center of the cylinder from one another. Furthermore, the latch arm may have a generally U-shaped cross-section with a base and first and second leg portions. The first and second leg portions may each terminate in an elongated row of teeth and are aligned with a respective adjacent one of the first and second teeth supported flange portions of the first slide member. The teeth of the first and second leg portions engage the teeth of the respective adjacent flange portions when the latch arm is in the first position.
As a further aspect of an embodiment, the housing may include a second wall opposite to the first wall, the second wall including an arm flange receiving opening therein. The latch arm includes an arm flange projecting outwardly from the base toward the arm flange receiving opening. An actuator guide flange also projects outwardly from the second wall of the housing with the guide flange defining the actuator guide slot. A fluid actuator is provided for operating the latch, the actuator having an actuator cylinder which is pivoted to the housing, an actuator piston within the actuator cylinder, and an actuator piston rod. The actuator piston rod has an end portion projecting outwardly from the actuator cylinder. A link pivotally couples the end portion of the actuator piston rod to the latch arm flange. The end portion of the actuator piston rod is also coupled to the actuator guide flange such that the actuator guide slot guides the movement of the actuator piston rod during extension and retraction of the actuator piston rod. In this example, extension of the actuator piston rod shifts the latch arm to the first position and retraction of the actuator piston rod shifts the latch arm to the second position.
As yet another aspect of an embodiment, the shock absorber may be adapted to provide a non-linear dampening force to the seat to dampen seat vibrations. For example, the dampening force may be constant for a first range of movement of the seat in response to vibrations from a home position of the dampening piston and increasing for certain movements of the dampening piston in excess of the first range of movement.
In accordance with another embodiment, first and second latch arms are pivoted to the housing and are disposed at opposite sides of a cylinder disposed substantially within the housing. These latch arms each have a central portion and first and second end portions. The latch arms each pivot about an axis through a central portion of the latch arm. The first end portion of each latch arm includes a latch surface and the cylinder has an exterior with an elongated latch gripping surface. A fluid actuator is coupled to the second end of each of the arms by respective links. Extension and retraction of the fluid actuator, and more particularly of an actuator piston rod, is translated through the links into pivoting motion of the first and second latch arms between respective first positions in which latch surfaces of the latch arms engage the latch gripping surfaces of the cylinder and second positions in which the latch surface and latch gripping surfaces are disengaged.
The present invention is directed toward novel and non-obvious features of a vibration dampener, both individually and collectively, as set forth above and as additionally set forth in the drawings and description which follows.